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Joel Andersson

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Slide 1

Flygteknik 2010

18 - 19 Oktober 2010

ASSESSING THE WELDABILITY OF NICKEL BASED SUPERALLOYS

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Joel Andersson

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Slide 2

Volvo Aero Components

Hot Structural Parts

Maximum Temperatures for Hot Structural Part Alloys of Interest:

718Plus: 700°C Waspaloy: 750 °CAlloy 718: 650°C

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Joel Andersson

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Slide 3

Flygteknik 2010

18 - 19 Oktober 2010

”Back to the Future”Weld Assemblies Make it Light

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Slide 4

Flygteknik 2010

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Slide 5

Welding Simulation at Volvo Aero

Flygteknik 2010

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Slide 6

Process

Material mechanisms

Experience/Testing

Expert/Modeling

Generic Knowledge Process

?

Gen

eric

Weld Cracking

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10110 Utg. 12

Slide 7

Weldability?

Flygteknik 2010

18 - 19 Oktober 2010

To describe a material’s ability to be readily fabricated, to perform in service, or both.

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Slide 8

Material’s resistance to cracking during fabrication

Hot cracking

– Cracks associated with the presence of liquid in the fusion and heat affected zone

Warm cracking

– Occurs at elevated temperatures in the solid-state, i.e. no liquid is present

Cold cracking

– Occurs at ”low” temperature and is usually related to embrittling species

Flygteknik 2010

18 - 19 Oktober 2010

Weldability

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10110 Utg. 12

Slide 9

Self-restraint test

– i.e. Circle patch

Simulative tests

– Involves tension or bending to simulate high restraint levels in welds.

Hot ductility tests

– Measure the strength and ductility at elevated temperatures.

Flygteknik 2010

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Weldability Testing - Hot Cracking

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Slide 10

Flygteknik 2010

18 - 19 Oktober 2010

Material Form Influence Weldability!

Cast Wrought

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Slide 11

Homogenization of Cast MaterialA

S-C

AS

T

10

5

1

1050 112511001075 12001150 1175

100μm

100μm

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Slide 12

Chemistry?

– Melting point depressant and eutectic forming elements, e.g Nb, C, Si…

– Harderners, e.g. Al and Ti

– Trace elements like B, P and S

Flygteknik 2010

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In Addition, Chemistry!

Hot Cracking and Strain Age Cracking (Warm cracking)

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Slide 13

Superalloy Chemistry

Chemistry – wrought

Niobium

– Segregation

Result of segregation

– Carbides

– Laves eutectics

Alloy/Element Ni Fe Cr Co Mo Nb Ti Al W C P BWaspaloy Bal. - 19.4 13,3 4.3 - 3.0 1.30 - 0.035 0.006 0.006

Alloy 718 Bal. 18.0 18.1 - 2.9 5.40 1.0 0.45 - 0.025 0.007 0.004

Allvac® 718Plus Bal. 10.0 18.0 9.0 2.8 5.45 0.7 1.45 1.0 0.025 0.014 0.006

Flygteknik 2010

Wt%

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Slide 14

1050 1100 1150 1200 1250 1300 1350 1400 1450Temperature /°C

-150

-100

-50

0

DSC /mW

On-Heating

MC Reaction

MC ReactionLaves Reaction

Solidification StartsOn-Cooling

Melting Completed

[1.1]

[1.3]

exo

718718Plus Waspaloy

Chalmers University of Technology

DSC JMatPro

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Slide 15

”Bend tests” at Aalto University, Finland

Transvarestraint Provning Varestraint Provning

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Slide 16

QUENCH SYSTEM TEST CHAMBER

PROGRAMMING UNIT

GLEEBLE CONTROLLING

UNIT

SAMPLE

THERMOCOUPLES

GRIPS GRIPS

QUENCH SYSTEM

TEST CHAMBER

Gleeble test at University of Manitoba, Canada

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Slide 17

Flygteknik 2010

18 - 19 Oktober 2010

Hot Ductility

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Slide 18

Weld trials at Volvo Aero

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Slide 19

Aging Diagram’Strain Age Cracking’

Te

mp

era

ture

, ºC

Time, sec

1 10 100 1000 10000

500

’

’’

Heating

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Slide 20

Ni 3(Al,Ti)

’

Weldability limit

Strain Age Cracking Diagram

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Slide 21

Summary

Flygteknik 2010

Manufacturing Repair

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Slide 22

Welding metallurgy must be fully understood!

– Integrated with welding simulation!

Weldability in general (metallurgical standpoint)

– Eutectic forming elements

Hot ductility Hot Cracking

Ability to heal cracks

– Hardeners such as Al and Ti SAC

Flygteknik 2010

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Summary

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Slide 23

Flygteknik 2010

18 - 19 Oktober 2010

Thank you!

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Slide 24

Flygteknik 2010

18 - 19 Oktober 2010